Question Ram dropped by half, after installing new GPU

[kineticnrgie]

Hello.
I just installed a Radeon RX 570 8G and suddenly I notice that in the system it says that I only have 4 GB ram, when in reality I've got 8GB (4x2GB).

The only thing I touched was the GPU.
After that I've opened up the case and checked if I could have touched the rams but everything is ok.

I took off the GPU and tried the old one and I get 8GB ram again.....

Any thoughts?

Thanks

 

[rgd1101]

full system spec? include make and model of the psu

 

[kineticnrgie]

Asus F2A85-M mobo with an AMD A6 6400K
8GB DDR3 ram
Radeon RX570 8GB
1 SSD (240GB)
2 HDD (160GB 7200rpm and 1TB 5400rpm)
PSU Tacens Mars Gaming MP700 (700W)